There have been many attempts to achieve an insulating material having a down-like structure and qualities for use in insulating articles such as clothing, sleeping bags, comforters, and the like. Prior efforts to develop a feasible material have often yielded those with a structure dissimilar from real down, are too heavy and dense to be considered down-like, and/or are difficult to blow through conventional equipment.
These include the following by way of example:
U.S. Pat. No. 988,010 is a labor intensive means of producing a material described as simulating a feather. While twisting is used to achieve the divergence or “fanning” of the individual filaments, this patent teaches two separate components to make a “feather”.
U.S. Pat. No. 2,713,547 uses chicken feathers or biers glued to a monofilament to produce a simulated down.
U.S. Pat. No. 3,541,653 is a means of producing high bulk yarns by sewing and slitting matts comprised of bulkable synthetic continuous filaments.
U.S. Pat. No. 3,892,919 describes a filling material using larger cylindrical or spherical formed fiber bodies along with feathery formed bodies which are mixed together with the latter relied upon to fill the voids.
U.S. Pat. No. 4,040,371 describes a polyester fiber filling material comprising a blend of polyester staple fibers with organic staple fibers.
U.S. Pat. No. 4,167,604 describes an improved thermal insulation material that is a blend of down and synthetic fiber staple formed from hollow polyester filaments which may be treated with silicone and formed into a carded web.
U.S. Pat. No. 4,248,927 describes an insulating material comprising a combination of natural feathers and downs, and synthetic polyesters formed into a web.
U.S. Pat. No. 4,259,400 provides a padding material that imitates natural feathers and consists of a flexible filiform textile rod on either side of which textiles fibers are bonded.
U.S. Pat. No. 4,468,336 describes loose fill insulation that is blown into spaces. The insulation material comprises a mixture of loose fill cellulosic insulation mixed with a staple fiber.
An exception to the aforementioned drawbacks is U.S. Pat. No. 4,588,635 which discloses a superior synthetic down and has particular reference to light-weight thermal insulation systems which can be achieved by the use of fine fibers in low density assemblies and describes a range of fiber mixtures, that, when used to fabricate an insulating batt, provides advantageous, down-like qualities such as a high warmth-to-weight ratio, a soft hand, and good compressional recovery. This material approaches, and in some cases might even exceed the thermal insulating properties of natural down. From a mechanical standpoint, the use of extremely fine fibers may result in concerns for rigidity and strength that make them difficult to produce, manipulate and use. Recovery properties of such a synthetic insulator material are enhanced at larger fiber diameters, but an increase in the large fiber component will seriously reduce the thermal insulating properties overall. The problems associated with mechanical stability of fine fiber assemblies are more of a concern in the wet condition since surface tension forces associated with the presence of capillary water are considerably greater than those due to gravitational forces or other normal use loading and they have a much more deleterious effect on the structure. However, unlike waterfowl down, the disclosed fiber combination does provide excellent resistance to wetting.
Another exception is U.S. Pat. No. 4,992,327 discloses the use of binder fiber components to improve insulator integrity without compromising desired attributes. More specifically the invention disclosed therein relates to synthetic fiber thermal insulator material in the form of a cohesive fiber structure, which structure comprises an assemblage of: (a) from 70 to 95 weight percent of synthetic polymeric microfibers having a diameter of from 3 to 12 microns; and (b) from 5 to 30 weight percent of synthetic polymeric macrofibers having a diameter of 12 to 50 microns, with at least some of the fibers are bonded at their contact points, the bonding being such that the density of the resultant structure is within the range 3 to 16 kg/m3. The thermal insulating properties of the bonded assemblage are equal to or not substantially less than the thermal insulating properties of a comparable unbonded assemblage. The reference also describes a down-like cluster form of the preferred fiber blends. The distinct performance advantages of the cluster form over the batt form are also disclosed in the patent.
U.S. Pat. No. 5,057,116 describes insulation formed by blending binder fibers with insulative fibers. The insulative fibers are selected from the group consisting of synthetic and natural fibers formed into a batt which may be cut into any desired shape.
U.S. Pat. No. 5,458,971 describes a fiber blend useful as a fiberfill in garments. The fiberfill blend comprises crimped hollow polyester fiber and crimped binder fibers.
U.S. Pat. No. 5,492,580 describes a material formed by blending a mix of first thermoplastic, thermoset, inorganic, or organic fibers with second thermoplastic fibers.
U.S. Pat. No. 5,624,742 describes a blowing insulation that comprises a blend of first and second insulating (glass) fiber materials. One of the groups of fibers is smaller in size for filling the voids between the fibers of the larger group.
However, prior art clusters often are generally hand fabricated in a slow, tedious, batch process. Furthermore, some of the prior art materials are not easily blowable materials which can be used with conventional manufacturing equipment.
It should also be noted that prior art insulation material may take various forms such as staple fibers of various sizes, hollow and solid fibers, and crimped fibers, among others. Various shapes have also been suggested such as spheres (U.S. Pat. No. 4,065,599), spheres with projecting fibers to allow for interlocking (U.S. Pat. No. 4,820,574), crimped bundles of fibers (U.S. Pat. No. 4,418,103), assemblies of looped fibers (U.S. Pat. No. 4,555,421), rolls of fibers, bails, bundles and pin cushion configurations (U.S. Pat. No. 3,892,909), just to mention a few.
In addition, clusters of fibers formed from shredded batt, such as that disclosed in U.S. Pat. No. 6,329,051 entitled “Blowable Insulation Clusters”, and such clusters in an admixture with natural fibers such as down, as disclosed in U.S. Pat. No. 6,329,052 entitled “Blowable Insulation”, have been found particularly suitable as insulation/fill material.
Various ways of creating an alternative but related form of insulation include fiber fill or fiber balls. Other forms of synthetic alternatives to natural insulation include that disclosed in U.S. Pat. No. 5,851,665 which describes point bonding of tows of fibers. Another way, as disclosed in U.S. Pat. No. 5,218,740 is to feed a uniform layer of staple fiber into a rotating cylinder covered with card clothing and rolling the fiber into rounded clusters which are removed by a special doffer screen. Others suggest blowing or air tumbling the fiber into a ball. (See e.g. U.S. Pat. Nos. 4,618,531; 4,783,364; and 4,164,534.)
While some or all of the foregoing references have certain attendant advantages, further improvements and/or alternative forms, is always desirable.